This invention relates to intraocular lenses and in particular to intraocular lenses (IOL's) which reduce secondary opacification.
An intraocular lens is commonly used to replace the natural lens of the human eye when warranted by medical conditions. It is common practice to implant an IOL in a region of the eye known as the capsular bag or posterior capsule.
One problem that is experienced with many IOL's following their implantation is that cells from the eye, particularly lens epithelial cells from the capsular bag, tend to grow on the capsular bag in front of and/or in back of the optical portion of the IOL. This tends to block the optical portion of the IOL and to impair vision.
A common treatment for this condition is to use a laser to destroy the cells and a central region of the capsular bag. Although this treatment is effective, the laser is expensive and is not available throughout the world. There is also cost associated with the laser treatment as well as some patient inconvenience and risk of complications. Finally, the laser treatment may affect the performance of some IOL's.
Davenport U.S. Pat. No. 4,743,254 discloses an IOL which includes glare reducing sections on the opposite sides of an optic. These glare reducing sections are fully or partially opaque and their surfaces are not smooth. It has been observed that cell migration across the glare reducing sections appears to be reduced. A similar result has been observed in a plate IOL in which a plate, which is used as a haptic for fixing the IOL in the eye, surrounds the optic. Specifically cell migration across the plate, which has a somewhat textured surface, appears to be reduced.
Kelman U.S. Pat. No. 4,808,181 discloses an IOL including a lens assembly having an anterior surface formation and a posterior surface formation. At least a portion of the posterior surface formation constitutes a planar contact region adapted to seat against the posterior capsule of the eye to permanently anchor the lens assembly. The contact region is provided with a roughened surface area defined by a series of ordered narrow linear depressions extending transverse of the plane of the contact region. This patent teaches that these ordered narrow linear depressions accelerate adhesion and enhance anchoring of the tissue of the posterior capsule to the lens assembly. This patent is not concerned with secondary opacification and provides no solution to this problem.